Ballast device for electric-lamp circuits.



No. 743,029. PATBNTED NOV. 3, 1903. H. N. POTTER.

BALLAST DEVICE FOR ELECTRIC LAMP CIRCUITS.

I APPLICATION FILED DBO. 29. 1899.

N0 MODEL.

ATTORNEY n1: NORRIS vzrzns 0o. PHOTOMYNO. WASHINGTON. D c.

UNITED STATES IPatented November 3, PATENT OFFICE.

HENRY NOEL POTTER, OF'PITTSBURG, PENNSYLVANIA, A SSIGNOR TO GEORGE WESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA.

BALLAST DEVICE FOR ELECTRIC-LAMP CIRCUITS.

SPECIFICATION forming part of Letters Patent No. 743,029, dated November 3,1903.

. Application filed December 29, 1899. Serial No. 741,975. (No model.)

To all whom it may concern:

Be it known that I, HENRY NOEL POTTER, a citizen of the United States, and a resident of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvementsin Ballast Devices for Electric-Lamp Circuits, of which the following is a specification.

In operating electric lamps having glowers that are conductors only when hot and the resistance of which decreases as the temperature increases it is customary to provide each glower with a ballast resistance, so as to counteract the decreasing resistance of the glower by an increase in its own resistance as the current through the glower and the ballast increases.

I have made-use of a ballast resistance composed of a material which has a large cor-T rective effect within a critical region which lies at a comparatively high temperature. One of the materials which I have employed for this purpose is iron wire, so proportioned that it is brought to an approximately dullred heat by the normal operating-current for the glower. One of the advantages arising from the use of this material is that it may have small weight, and therefore small specific heat, and that it arrives atits temperature of maximum correction quickly on starting up the lamp.

It has been the practice prior to my present invention to place the ballast resistance, of whatever character it may be, in series with the glower, but in shunt to the heater, by means of which the glower is brought to a conductive state. Even with the best ballast resistances when so arranged it sometimes happens that a shooting over of the current takes place at the initial closure of the lamp-circuit, resulting in inj ury to the glower. I have discovered that this shooting over may be avoided by connecting the ballast resistance in the common circuit of the heater and glower, or, it connected in shunt to the heater,

by locating it in proximity to means for raising its temperature while the temperature of the glower is increased. The arrangements described possess especial advantages when the ballast resistance responds comparatively slowly to changes in current, as is the case in coiled ballast-conductors. Inasmuch as the glower-circuit does not become operative until the heater has raised the glower to a conductive temperature, whereas the heatercurrent, whereby the tendency of the current to shoot over and injure or destroy the glower is obviated.

In the accompanying drawings, Figure 1 represents diagrammatically an electric lamp containing the usual glower and heater and the usual cut-out devices, together with my improved ballast resistance located in a circuit common to the glower and heater. Fig. 2 is a similar view of a modified arrangement for effecting substantially the same result.

In Fig. 1 of the drawings, 1 and 2 are mains leading from any suitable generator of electricity. 3 is a ballast resistance consisting of a coil 4: of wire supported by leading-in wires 15 and 16 Within a glass bulb 5. 6 is the heater contained in a branch circuit, which includes also the stationary terminals 7 and 8 of an automatic cut-out switch 9. Cooperating with the terminals 7 and 8 are movable terminals 10 and 11, secured to the end of a core 12, which is adapted to move longitudinally within a coil or solenoid 13 in series with a glower 14. The glower is composed of one or more of the dry electrolytessuch as zirconia, yttria, or the 1ike-and it has the quality, as is well known, of becoming conductive under the influence of heat, the heat in the first instance being supplied by an exhating-body.

the coil of iron wire 4, and through the heater- 6 and the switch 9 to the opposite main. The effect of the current is to raise the temperature not only of the heater 6, but also of the iron wire 4. By the time the glower 14 has been brought to a conductive temperature the temperature of the iron wire 4 has been raised to such a degree that the tendency of the current to rush through the glower is cor.- rected by the rapidly-increasingresistance of the wire 4. The automatic switch or cut-out 9 operates in the usual way to break the heater-circuit as soon as the glower-circuit carries enough current to keep the glower incandescent without external heat. The ballast resistance in this arrangement is placed in the common circuit of the heater and glower, and it is by virtue of this placing of the ballast that the glower is protected from an excessive inrush of current on the starting of the lamp.

In the arrangement shown in Fig. 2 the operating parts are in general the same as those shown in Fig. l, and, except as hereinafter specified, they are marked by the same reference-numerals and will not be again described. In this modification the ballast-conductor 4 is not connected in circuit with the heater 6, but is located in proximity to a heating device, here shown as a length of wire 16*, forming part of the heater-circuit within the bulb 3 and of such composition and resistance as to generate the desired degree of heat without being destroyed or materially injured by it.

In order to produce corrective effects by means of the ballast resistance sufficient to counteract the danger of an injurious inrush of the current on the starting of the lamp, it is not necessary to bring the ballast to the temperature at which its greatest corrective effects are present, but it may be sufficient to effect only a slight increase in the teinperature of the ballast resistance.

I make no claim herein for the method of protecting lamp-glowers from injurious inrush of current at starting, but have made such method the subject-matter of a divisional application, filed February 14, 1901, Serial No. 47,354.

The invention claimed is 1. In an illuminating apparatus, the combination of an illuminating body or conductor of the second class, a resistance in series therewith when the lighting-current flows, and means for heating the said resistance before the passage of the illuminating-current through the said resistance and the illumi- 2. In a lighting apparatus, the combination of a glower composed of a conductor of the second class, a, resistance in circuit therewith when the lighting-current flows, composed of a material having a high-temperature coefficient, and means for heating the said resistance just beforethe passage of the illuminating-current through the resistance and the glower.

3. The combination with a glower of the type described and an electric heater therefor, of a ballast resistance located in the common circuit of the said glower and heater.

4. The combination with a glower of the type described and an electric heater therefor, of a ballast resistancelocated in the common circuit of said glower and heater, and automatic devices for breaking the heateroircuit after the glower has reached a state of incandescence.

5. The combination with a glower of the type described and an electric heater therefor, of a ballast located in the common circuit of the said glower and heater, the said ballast having a critical region lying at a high temperature within which region its resistance automatically increases to an exceptional extent with slight increments of temperature.

6. The combination with a glower of the type described and an electric heater therefor, of a ballast for the glower located in the common circuit of the said glower and heater, the said ballast having a critical region lying at or about a 'red heat within which region its resistance is automatically increasable to an exceptional extent by a slight increase of the normal operating-current of the glower.

7. An electric lamp of the type described embodying a glower, a heater therefor, a ballast resistance and means for raising the temperature of said ballast resistance while the heater is raising the temperature of the glower to the conductive degree.

8. An electric lamp of the type described comprising a glower, an electric heater therefor, a ballast resistance and means for effecting a temperature rise in the ballast-conductor during the period of heating the glower to conductive temperature.

9. In an electric glow-lamp, the combination of a glower of second-class conducting material, an initial resistance in circuit therewith when the lighting-current flows, and a common means for heating both the resistance and the glower prior to the passage of current therethrough.

Signed at Pittsburg, in the county of Allegheny and State of Pennsylvania, this 21st day of December, A. D. 1899.

HENRY NOEL POTTER.

Witnesses:

H. A. OROOK, W. D. UPTEGRAFF. 

